Teen boy, 19, believed to be youngest particular person to ever be identified with dementia

Doctors in China have identified the world’s youngest case of Alzheimer’s disease in a 19-year-old, yet scientists are baffled as to how he developed the memory-robbing condition at such a young age.

The unnamed teen boy first began experiencing memory decline at 17. He often forgot what he did the day before and was always misplacing his belongings. He was eventually unable to graduate from high school, though he could still live on his own.

Before he was formally diagnosed with early-onset Alzheimer’s, the teen was sent to a memory care clinic for about a year, where experts found that his overall memory score was 82 percent lower than that of his peers of the same age and his immediate memory score was 87 percent lower.

In 2022, brain scans showed shrinkage in the hippocampus, a crucial memory formation region in the brain and one of the first areas affected by Alzheimer’s, the most common form of dementia that affects roughly 6.7 million Americans.

Doctors at that clinic analyzed his cerebrospinal fluid and detected telltale markers of the disease, including abnormal levels of amyloid and tau proteins.

When they conducted a thorough search of his DNA for mutations that made him more susceptible to the disease, they found nothing.

Almost all patients diagnosed under the age of 30 have specific genetic mutations, typically in genes like PSEN1, leading to a classification of familial Alzheimer’s disease. This unidentified man, however, had no such mutations nor any family history of dementia, ruling out known disease pathways. 

Researchers from Capital Medical University, who described the patient, noted that the disease’s ‘pathogenesis still needs to be explored,’ implying that undiscovered genetic factors, unique environmental interaction or never-before-documented disease pathways could be at play.

The unnamed teen’s memory decline began at age 17, with symptoms like forgetting the previous day and constantly misplacing items. This progressed to the point where he could not finish high school (stock)

To date, the youngest person known to have been diagnosed with Alzheimer’s disease was 21 years old and carried the PSEN1 gene mutation. This young man’s case, though, appears to be ‘sporadic,’ according to the researchers, with causes unknown. 

This 19-year-old patient is the youngest known case of Alzheimer’s disease with no known genetic contribution, according to the researchers. 

Their case report, published in the Journal of Alzheimer’s Disease, said: ‘Although the patient’s age of onset is very early, he met the diagnostic criteria for probable AD dementia, according to the diagnostic criteria of the National Institute on Aging-Alzheimer’s Association.’ 

This teenager’s decline was both quick and debilitating. Beginning with concentration problems in high school, he soon faced profound short-term memory loss marked by forgetting daily events, misplacing belongings and struggling to retain even a paragraph of text.

On standard cognitive screening tests, when he first got to the memory clinic, the young man’s scores appeared normal. He scored 28 out of 30 on the Montreal Cognitive Assessment (MoCA), where a score of 26 or higher is considered normal, and 29 out of 30 on the Mini-Mental State Examination (MMSE), where a score of 24 or higher is normal.

However, a year later, he lost points specifically in the MoCA’s memory section. Further testing revealed the true severity of his condition. His scores on specialized memory testing were extremely abnormal.

He recalled only 37 words over five immediate trials. The normal figure is about 56 for his age and education-matched peers. He recalled five words after a three-minute delay, whereas it should be roughly 13 and a mere two words after 30 minutes, where the normal is also about 13. 

His profound memory deficit, placing him below 82 to 87 percent of people his age, revealed significant impairment that initial tests had failed to capture.

An MRI showed the patient’s hippocampus, the brain’s memory center, had begun to shrink and other scans confirmed reduced activity in other key memory regions.

The patient’s MRI showed that the brain’s memory center (the hippocampus) and critical thinking areas (the parietal and temporal cortices) have visibly shrunk in size, indicated with arrows pointing to those spots

Specialized PET scans designed to detect the classic Alzheimer’s proteins, amyloid and tau, came back negative, showing no obvious buildup.

But when doctors performed a lumbar puncture to extract and analyze his cerebrospinal fluid, doctors found elevated levels of tau proteins and an abnormal ratio of amyloid proteins.

The specialized amyloid PET scan has its limitations, particularly in detecting the earliest stages of the disease. These scans can fail to identify plaques in a small yet significant portion of people with confirmed Alzheimer’s. But spinal fluid tests are often more sensitive early on.

An exhaustive battery of other tests ruled out alternative causes of his memory decline. 

There were no signs of infections, autoimmune disorders, toxins or other metabolic diseases. Meanwhile, genetic testing did not show any mutations in PSEN1, PSEN2 or APP genes that typically cause early-onset Alzheimer’s.

He also had the most common, neutral form of the APOE gene, two copies of which drastically increase a person’s likelihood of developing Alzheimer’s.

Alzheimer’s is typically a disease of the elderly, but recent studies have suggested rates among people under 50 are on the rise. 

According to a report from Blue Cross Blue Shield, diagnoses among commercially insured adults aged 30 to 64 surged by 200 percent between 2013 and 2017. 

Jana Nelson’s life transformed in her late 40s when the formerly easygoing businesswoman began experiencing severe mood swings, balance issues, and cognitive decline. After extensive testing, she received the devastating diagnosis of early-onset dementia at age 50

Rebecca, a 48-year-old single mother, was diagnosed with early-onset Alzheimer’s after years of memory lapses. Facing a rapid decline and a stark prognosis, she has chosen to end her life through Canada’s medical assistance in dying program before the disease takes full control

The average person affected is just 49 years old, and the condition disproportionately impacts women, who account for 58 percent of cases. 

The sharp rise in early-onset dementia diagnoses may largely reflect better detection, not a true explosion in cases. Historically, cognitive symptoms in younger adults were routinely misattributed to stress or burnout, leading to widespread underdiagnosis. 

Modern lifestyle factors such as poor diet, physical inactivity, high screen time and obesity are now under scientific scrutiny as potential contributors to the rising risk of dementia, particularly among younger people.

Research is examining whether these interconnected factors drive inflammation, vascular damage and metabolic dysfunction, which may collectively accelerate brain aging and cognitive decline long before the onset of old age.